Woman with an Enlarging Lesion on Nose

Specimen Type:

Skin

History:

A 79-year-old woman had a 25 year history of enlarging lesion on her nose. The clinical diagnosis was tumor of uncertain etiology.

Pathologic Features:

The specimen consists of a large well-circumscribed, polyploid tumor composed of multiple interconnecting lobules and broad strands of germinative cells and cells with sebaceous differentiation. Ductal formation and a focal chondroid stroma were present. The lobules are generally rounded without an infiltrating pattern. In areas, the cells were mildly pleomorphic with crowding and scattered mitotic figures were identified.

Differential Diagnosis:

Sebaceoma

Sebaceous adenoma

Sebaceous carcinoma

Diagnosis:

Sebaceoma

The 25-year history, sharp circumscription with symmetry, predominance of germinative cells, lack of significant atypia and only a few mitotic figures are supportive of the diagnosis of a sebaceoma. A sebaceous adenoma tends to be smaller in size and have a predominance of mature sebaceous cells. These two lesions can be considered as part of a continuum based on size and proportion of germnative cells to mature sebaceous cells. A sebaceous carcinoma generally has well developed cytologic atypia, an increased number of mitotic figures including atypical forms and an infiltrating growth pattern.

The importance of these adnexal tumors to the patient and the physician is their recognition as potential markers of genetic syndromes, especially those related to internal cancer. Multiple sebaceous gland tumors have been associated with the Torre-Muir syndrome which has the potential to develop colorectal carcinoma and other malignancies including those involving the uterus, renal pelvis, and breast. The sebaceous gland tumors may precede the development of these internal malignancies by many years. The Torre-Muir syndrome is considered to be a subset of the hereditary non-polyposis colorectal carcinoma syndrome and is associated with microsatellite instability resulting from loss of DNA mismatch repair proteins. Multiple sebaceous tumors and/or sebaceous tumors occurring before the age of 50 years are considered strong indicators of the Torre-Muir syndrome.